In electrical engineering and mechanical engineering, a transient response is the response of a system to a change from an equilibrium or a steady state. The transient response is not necessarily tied to abrupt events but to any event that affects the equilibrium of the system. The impulse response and step response are transient responses to a specific input (an impulse and a step, respectively).
In electrical engineering specifically, the transient response is the circuit’s temporary response that will die out with time.[1] It is followed by the steady state response, which is the behavior of the circuit a long time after an external excitation is applied.[1]